Access S3 Bucket From Private Subnet EC2 Instance

Introduction

In this article, we are going to learn how we can access the S3 bucket in a Private subnet EC2 Instance. So before diving in, let's learn the basic terms first.

S3 Bucket

S3 Stands for Simple Storage Service and it is a cloud storage service available in AWS. Basically S3 in Amazon has two entities, objects and buckets. Objects are stored inside buckets and every organization needs a file system to store their unstructured files, that's why AWS introduced a file system called S3

Private Subnet instance

It can not be accessible from the internet directly which means nobody can enter this subnet directly. Generally, we put database servers and S3 buckets in private instances and they can access via a NAT gateway that resides in public subnets.to use the NAT gateway we require VPC, and I already explained in my last article how we can create a private subnet EC2 instance here

Let's start with creating an S3 bucket.

How to Create S3 Bucket in AWS

It works like this. You upload an image in the traditional way, create a file uploading this, and store it into an S3 bucket which can be accessed anywhere in the world from any device.

By default, the maximum number of buckets that can be created per account is 100, and bucket names have to be globally unique as buckets can be accessed using URLs so it is recommended to create a bucket that follows some naming conventions. let's create an S3 bucket in AWS.

Step 1

Search the S3 bucket in the main search bar and a page is open under Amazon S3 -> buckets, click on create bucket button and give the unique name to the bucket, and select the AWS region where you want to put the S3 bucket. you can also select the existing bucket if you want to apply the same setting to this bucket.

Access S3 bucket from Private Subnet EC2 Instance

Step 2

Next option is the Account control list(ACL) option- if you want to allow this bucket to be used by other AWS accounts also then you can enable the ACLs otherwise continue with the default option

Access S3 bucket from Private Subnet EC2 Instance

Step 3

Here, there are options to select the further public access, it is recommended to block all public access but sometimes if you enable ACLs then you have further access options here as of now we block all public access and continue

Step 4

The bucket Versioning option is also available where you can keep multiple versions of an object in the bucket. This is used to restore the earlier version of file if you upload a newer version of an object unintentionally.

Access S3 bucket from Private Subnet EC2 Instance

Step 5

You can tag your bucket to remember the purpose of the bucket. I create a tag that this bucket is for a private subnet like this you can give any tag.

Access S3 bucket from Private Subnet EC2 Instance

Step 6

Default encryption, this option allow you to allow the automatic encryption of new objects stored in the bucket.

Access S3 bucket from Private Subnet EC2 Instance

Click on create bucket now.

Access S3 bucket from Private Subnet EC2 Instance

Now if we access the S3 from our EC2 instance, we are not able to see the S3 buckets directly, for this we have to create the role and assign the policies and then modify the IAM access for this instance

Next is to apply policies on the S3 bucket to allow for access from the EC2 instance private subnet.

Step 7 - Create a role and assign policies for S3 Bucket Permission

To create a role navigate to IAM and click on roles and then click on create role button, select the AWS service as trusted entity type, and select use case as EC2 as we need to give access to an EC2 instance, click Next

Access S3 bucket from Private Subnet EC2 Instance

Step 8

Add Permissions, search S3 in the search bar, you have some pre-created policies or you can create your own policy as per your requirement. For now, I selected Amazons3FullAccess which provides full access to all buckets

Access S3 bucket from Private Subnet EC2 Instance

Step 9

Name & review the roles and policies, you can add the tags here as well in the below -

Access S3 bucket from Private Subnet EC2 Instance

After creating a role, it reflects in the Role list

Access S3 bucket from Private Subnet EC2 Instance

Step 10

Assign this role to a Private subnet EC2 instance, select the EC2 instance and click on actions then in security, there is an option of Modify IAM role click on this.

Access S3 bucket from Private Subnet EC2 Instance

Step 10

Select the respective role from the list, here we need to select FullS3Access role which we created earlier.

Access S3 bucket from Private Subnet EC2 Instance

Now we have the policies to access the S3 bucket to the private subnet EC2 instance and if we run the following command again, you can see all the buckets existed in the S3 bucket and myarticlebucket is also there which we created earlier.

Summary

This article describes how you can assign the policies to the private subnet EC2 instance and access all S3 buckets from there just by assigning some policies to the role and modifying the IAM role of the Instance to this newly created role.

I hope you like this article. Stay safe and learn more!